Attoenet



(No- Model.) I

L. K. BOHM.

COMBINATION VACUUM PUMP. No. 248,279. Patented Oct. 18,1881.

INVENTOR H BY ATTORNEY.

v UNITED STATES PATENT OFFICE;

LUDWIG K. BCHM, OF NEW YORK, N. Y., ASSIGNOR TO THE AMERICAN ELECTRICLIGHT COMPANY, OF SAME PLACE.

COMBINATION VACUUM-PUMP.

SPECIFICATION forming part of Letters Patent No. 248,279, dated October18, 1881.

Application filed July "I, 1881. (No model.)

To all whom it may concern Be it known that I, LUDWIG K. BCHM, of thecity, county, and State of New York, have invented certain new anduseful Improvements in Combination Vacuum-Pumps, of which the followingis a specification.

This invention refers to improvements in.combination vacuum-pumps forproducing high vacua, in which the well-known Geissler and Sprengelsystems are combined in a-more simple and effective manner thanheretofore, and by which electric lamps and other articles can beevacuated in a quicker and more reliable manner.

The combination-pumps heretoforein general use for laboratory purposeswere too complicated for practical purposes, as they were easilyinjured, and as the lifting of the mercury after each working of theSprengel pump into the reservoir of the same has been a greatinconvenience in working the pump. To obviate these objections theconstruction is greatly simplified, and, furthermore, the pressure ofthe atmosphere employed automatically for working the Sprengel pump.

The invention consists of the combination of a well-known Geissler and aSpren gel yacuurn- 1 pump with an intermediate connecting portion,

to which both systems are connected by ground glass joints. Theconnecting portion supports the drying-vessel and the tube withstop-cock,

- to which the lamp or other vessel is applied for evacuation.

The Sprengel pump is provided with a supply-tube, which is bent downwardin the shape of an S and connected to a mercury-reservoir, so thatwhenever, by the action of the Geissler pump, the interior of the pumpsis evacuated, the atmospheric pressure upon the mercury will force thesame through the supply-tube and cause the automatic working of theSprengel pump.

; Theaccompanyingdrawingrepresentsafront elevation of my improvedcombination vacuumpump.

By reference to the drawing it will appear that my improved pumpconsists of three main parts-to wit, of a Geissler'vacuum-pump, A, aSprengel vacuum-pump, B, and an intermediate connecting portion, Ccarrying the airdrying vessel D. The evacuating-tubes a a of bothsyslemsAand B are connected by ground glass joints a a to branch pipes bof the inter mediate portion, 0, below the drying-vessel D, which ispartly filled with anhydric phosphoric acid.

The branch pipes 11 b are sealed to the bottom of the drying-vessel andextended to the interior of the same, the extension-tube 12 being curvedsidewise above the surface of the acid,

so that the air drawn through the drying-vessel impinges first upon thesurface of the same, and passes then through the tube 12 to the Geissleror Sprengel pump. It is thereby dried by coming in contact with thephosphoric acid, as is customary in this class of pumps.

To the neck of the drying-vessel D is secured, by a ground glass joint,d, the connecting-tube a, with a stop-cock, E. To the upper end of thetube E is applied the lamp or other vessel to be evacuated, beingthereto connected by a ground joint, as shown clearly in the drawing.The ad vantage of this construction is that both pump systems arebrought closer together, which makes them less bulky, and simpler andless expensive in construction.

The Sprengel system B is provided in the supply-tube B, above thedischarge end of the same in the fall-tube, with a contraction or waist,w, for which a separate application for Letters Patent is now pending inthe United States Patent Office. The supply-tube B is bent above thecontraction a: and extended in a downward direction to a distance equalto or somewhat greater than the length of barometric pressure, beingthen bent upward again at the lower end and connected to amercury-reservoir, B This arrangement has the advantage that wheneverthe interior spaces of the combina-tionpump are evacuatedby one or uesto work until. only a column of mercury equal in length to that ofbarometric pressure remains in the longer middle portion of thesupply-tube. In this manner the evacuation takes place not only in lesstime, but also with considerably less trouble than heretofore, as noskilled attendant is required for working the pump.

By lifting the mercury of both pumps by a suitable power instead of byhand it is of advantage that the mercury of the Sprengel system has onlyto be lifted to about halfits former height.

Having thus described my invention, I claim as new and desire to securebyLetters Patent 1. The combination of a Geissler pump, a Sprengel pump,an air-drying vessel, and an intermediate coupling connecting theexhausttubes of the respective pumps with each other and with thedrying-vessel, said coupling being united to said exhaust-tubes byground glassjoints, substantially as described.

2. In a combination vacuum-pump, the intermediate portion, 0, providedwith a dryingvessel, D, branch pipes 1) below the same, and a curvedextension-tube 1) within the vessel D, substantially as set forth.

3. The combination of a Geissler vacuumpump, a Sprengel pump, and anintermediate connection between the exhaust-tubes of the respectivepumps, the supply-pipe of the Sprengel pump being bent into S shape,extended downward, and provided with a mercury-reservoir at its lowerend, so as to utilize the atmospheric pressure when the Geissler systemhas been worked to a certain extent, substantially as described.

In testimony thatIclaim the foregoing as my invention I have signed myname, in presence of two witnesses, this 29th day of June, 1881.

LUDWIG K. BOHM.

\Vituesses:

PAUL GOEPEL, CARL KARP.

